Using the dosimetric data from three of the six imaging time points and the patient's weight, a patient-specific activity (mCi) of Iodine-131 will be calculated to deliver the desired total body dose of radiation (75 cGy). Patients will receive an infusion of unlabeled Tositumomab (450 mg) immediately followed by an infusion of the patient specific dose of tellurium-derived Iodine I 131 Tositumomab (35 mg) to deliver a total body dose (TBD) of 75 cGy. Patients will be followed closely obtaining safety information during the post-treatment period, and for response and safety at 3,6,and 12 months during the first year, annually thereafter up to five years, and annually for additional safety and outcomes information up to 10 years.